1. Field of the Invention
The present invention relates in general to a system for communicating in a wellbore, and in particular to a system for communicating in a wellbore utilizing acoustic signals.
2. Description of the Prior Art
At present, the oil and gas industry is expending significant amounts on research and development toward the problem of communicating data and control signals within a wellbore. Numerous prior art systems exist which allow for the passage of data and control signals within a wellbore, particularly during logging operations. However, a non-invasive communication technology for completion and production operations has not yet been perfected. The communication systems which may eventually be utilized during completion operations must be especially secure, and not susceptible to false actuation. This is true because many events occur during completion operations, such as the firing of perforating guns, the setting of liner hangers and the like, which are either impossible or difficult to reverse. This is, of course, especially true for perforation operations. If a perforating gun were to inadvertently or unintentionally discharge in a region of the wellbore which does not need perforations, considerable remedial work must be performed.
In complex perforation operations, a plurality of perforating guns are carried by a completion string. It is especially important that the command signal which is utilized to discharge one perforating gun not be confused with command signals which are utilized to actuate other perforating guns.